Note that Sidis come in "Mega" for extra width. The regular Sidi's were way too narrow for me so I picked up a pair of Dominator's in Mega for a 1/8" extra room all round. They're still pretty snug compared to the Diadora Gekos I wore for a while but feel really good. Especially in the winter when I layered on socks.

I also do what Wangster does and replaced the slippery Sidi sole with something more padded and with better arch support (for me at least).